The staff over at Instructables have designed and published their plans on how to make a nice Arduino-controlled waveform generator. Although you won't be replacing commercial equipment with it, the project is very easy to work with and they have also included plans for laser-cutting an enclosure to help move the project from the breadboard to a usable tool. You can generate sine, sawtooth, pulse and triangle waves of between 1 and around 50 kHz. Apart from the Arduino the rest of the circuitry fits nicely on an protoshield.

For more details and the instructions, visit the project page. And we're on twitter and Google+, so follow us for news and product updates as well.